TY  - JOUR
A1  - Rabia, Kaneez
A1  - Meng, Fanqi
A1  - Thomson, Mark David
A1  - Bykov, Maxim
A1  - Merlin, Roberto
A1  - Smaalen, Sander van
A1  - Roskos, Hartmut
T1  - Coherent photo-induced phonon emission in the charge-density-wave state of K0.3MoO3
T2  - New journal of physics
N2  - We report on the observation of coherent terahertz (THz) emission from the quasi-one-dimensional charge-density wave (CDW) system, blue bronze (K0.3MoO3), upon photo-excitation with ultrashort near-infrared optical pulses. The emission contains a broadband, low-frequency component due to the photo-Dember effect, which is present over the whole temperature range studied (30–300 K), as well as a narrow-band doublet centered at 1.5 THz, which is only observed in the CDW state and results from the generation of coherent transverse-optical phonons polarized perpendicular to the incommensurate CDW b-axis. As K0.3MoO3 is centrosymmetric, the lowest-order generation mechanism which can account for the polarization dependence of the phonon emission involves either a static surface field or quadrupolar terms due to the optical field gradients at the surface. This phonon signature is also present in the ground-state conductivity, and decays in strength with increasing temperature to vanish above $T\sim 100\,{\rm{K}}$, i.e. significantly below the CDW transition temperature. The temporal behavior of the phonon emission can be well described by a simple model with two coupled modes, which initially oscillate with opposite polarity.
KW  - charge density wave
KW  - phonon
KW  - terahertz
KW  - coherent emission
KW  - time-resolved
KW  - blue bronze
Y1  - 2019
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/49285
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-492854
SN  - 1367-2630
N1  - Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
VL  - 21
IS  - Art. 013013
SP  - 1
EP  - 12
PB  - Dt. Physikalische Ges. ; IOP
CY  - [Bad Honnef] ; [London]
ER  -